Methods of fabricating interconnects for semiconductor components

ABSTRACT

In one aspect, the invention encompasses a method of fabricating an interconnect for a semiconductor component. A semiconductor substrate is provided, and an opening is formed which extends entirely through the substrate. A first material is deposited along sidewalls of the opening at a temperature of less than or equal to about 200° C. The deposition can comprise one or both of atomic layer deposition and chemical vapor deposition, and the first material can comprise a metal nitride. A solder-wetting material is formed over a surface of the first material. The solder-wetting material can comprise, for example, nickel. Subsequently, solder is provided within the opening and over the solder-wetting material.

TECHNICAL FIELD

The invention pertains to methods of fabricating interconnects forsemiconductor components.

BACKGROUND OF THE INVENTION

Semiconductor components, such as dice, wafers and chip scale packages,are fabricated to include external contacts to allow electricalconnections to be made from the outside of the components to integratedcircuits contained on the components. A semiconductor die, for example,typically includes patterns of bond pads formed on a face of the die. Atthe wafer level, the bond pads are used for probe testing the integratedcircuits on the die. At the die level, the bond pads are used fortesting, and also for making electrical connections, such as wire bonds,for packaging. Typically, the bond pads comprise planar aluminum pads,or alternatively solder bumps on solder wettable pads.

The interconnects described above are but one type of interconnect thatcan be utilized with semiconductor components. Numerous other types ofinterconnects are known. For instance, semiconductor packages, such aschip scale packages, can utilize solder balls arranged in a dense array,such as a ball grid array (BGA), or fine ball grid array (FBGA).

FIGS. 1-5 illustrate an exemplary semiconductor component 10 havinginterconnects associated therewith. FIG. 1 is a top view of a fragmentof the component 10, and shows a plurality of conductive traces 12, 14,16, 18, 20, 22, 24, 26, 28, 30, 32, 34 and 36. The conductive tracesextend from inner lead bond pads 38, 40, 42, 44, 46, 48, 50, 52, 54, 56,58, 60 and 62 to outer lead bonds 64, 66, 68, 70, 72, 74, 76, 78, 80,82, 84, 86 and 88. The shown relative sizes of the outer lead bonds andinner lead bonds are for diagrammatic purposes only. Accordingly,although the inner lead bonds are shown uniform in size and larger thanthe outer lead bonds which are also uniform in size, it is to beunderstood that the constructions can also have inner lead bonds and/orouter lead bonds which are not uniform in size, and can have inner leadbonds which are smaller than the outer lead bonds.

FIGS. 2 and 3 show a top view and a cross-sectional side view of anexpanded region of the FIG. 1 fragment. Such views show that the trace18 is a layer 100 of conductive material. Outer lead bond 70 comprises asolder ball 102 over a nickel-containing solder-wettable material 104.Inner lead bond 44 comprises a solder interconnect 106 having aconductive material cap 108 thereover. Conductive material cap 108 cancomprise, for example, nickel and/or a solder ball.

Trace 100 can be referred to as a redistribution layer, in that itdistributes an electrical signal from the central location of the innerlead bond 44 to the laterally outward location of outer lead bond 70 andvice versa.

The semiconductor component of fragment 10 comprises a semiconductor die110 which can correspond to, for example, a monocrystalline siliconwafer. The die 110 has various levels of integrated circuitry (notshown) associated therewith. An electrically insulative passivationlayer 112 extends around die 110 and insulates the die from the soldermaterial 106. Passivation layer 112 can comprise, consist essentiallyof, or consist of silicon dioxide, and will typically have a thicknessof from about 2000 Å to about 8000 Å. An insulative material 114 isprovided over passivation layer 112, and is utilized to support circuittrace 100, and can also be utilized during patterning of circuit trace100. Layer 114 can comprise, for example, polyimide.

Semiconductor die 110 can be considered a semiconductor substrate, oralternatively the die 110 in combination with various other materials ofcomponent 10 can be considered a semiconductor substrate. To aid ininterpretation of the claims that follow, the terms “semiconductivesubstrate” and “semiconductor substrate” are defined to mean anyconstruction comprising semiconductive material, including, but notlimited to, bulk semiconductive materials such as a semiconductive wafer(either alone or in assemblies comprising other materials thereon), andsemiconductive material layers (either alone or in assemblies comprisingother materials). The term “substrate” refers to any supportingstructure, including, but not limited to, the semiconductive substratesdescribed above.

The die 110 has two opposing sides 111 and 113, which are typicallyreferred to as a front side and a back side, respectively. Component 10has opposing outer surfaces 115 and 117 that are proximate the frontside 111 and the back side 113, respectively, of die 110. Surfaces 115and 117 can be referred to as a front-side surface and back-sidesurface, respectively, of component 10.

Solder material 106 extends entirely through component 10, andaccordingly extends from the front-side surface 115 of the component tothe back-side surface 117 of the component. Solder material 106 canultimately be utilized for an electrical connection to an externaldevice proximate back-side surface 117, and can be utilized forelectrically interconnecting such device to another device associatedwith pad 102 of outer lead 70.

A method of forming the structure of FIGS. 2 and 3 is described withreference to FIGS. 4 and 5. Specifically, the construction 10 is shownprior to formation of leads 44 and 70 (FIGS. 2 and 3). A hole 130 isetched through component 10 to extend from front-side surface 115 toback-side surface 117. The hole can be formed by, for example,laser-etching. The hole comprises a depth 132 extending from thefront-side surface 115 to the back-side surface 117, and comprises awidth dimension 134 orthogonal to the depth. The hole can besubstantially circular when viewed from above (as shown), andaccordingly width dimension 134 can correspond to a diameter of thecircle. Alternatively, the hole can have a polygonal shape (such as, forexample, a square shape) when viewed from above. Regardless of the shapeof the hole 130, the maximum width dimension will typically be less thanor equal to about 100 microns, and frequently will be less than or equalto about 35 microns.

A problem is encountered in uniformly filling hole 130 with solder.Specifically, the small dimension of hole 130 makes it difficult to flowsolder into the hole. Various efforts have been made to providesolder-wetting agents along the peripheral sidewalls of the hole 130 inorder to draw the solder into the hole. However, the provision of thesolder-wetting agents will frequently comprise relativelyhigh-temperature processing (specifically, processing in excess of 300°C.), which can adversely impact circuitry associated with die 110.Accordingly, it is desired to develop new methods for forminginterconnects within semiconductor components.

SUMMARY OF THE INVENTION

In one aspect, the invention encompasses a method of fabricating aninterconnect for a semiconductor component. A semiconductor substrate isprovided, and an opening is formed which extends entirely through thesubstrate. A first material is deposited along sidewalls of the openingat a temperature of less than or equal to about 200° C. A secondmaterial is then plated within the opening and over the first material.

In one aspect, the invention encompasses a method of fabricating aninterconnect for a semiconductor component. A semiconductor substrate isprovided and an opening is formed to extend entirely through thesubstrate. A metal nitride is deposited along sidewalls of the opening.The deposition is conducted in a reaction chamber utilizing a firstprecursor containing the metal of the metal nitride, and a secondprecursor containing the nitrogen of the metal nitride. The depositioncomprises at least one cycle in which the first and second precursorsare in the reaction chamber at different and substantiallynon-overlapping time intervals relative to one another. A secondmaterial is subsequently plated within the opening and over the metalnitride.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described below withreference to the following accompanying drawings.

FIG. 1 is a diagrammatic top view of a prior art semiconductor componentconstruction.

FIG. 2 is an enlarged view of the region 2 of the FIG. 1 prior artconstruction.

FIG. 3 is a view along the line 3-3 of the FIG. 2 prior artconstruction.

FIG. 4 is a view of a prior art construction at a processing stage priorto that of FIG. 2.

FIG. 5 is a cross-sectional view along the line 5-5 of the FIG. 4 priorart construction.

FIG. 6 is a diagrammatic, cross-sectional view of a semiconductorcomponent at a preliminary processing stage of an exemplary method ofthe present invention.

FIG. 7 is a view of the FIG. 6 fragment shown at a processing stagesubsequent to that of FIG. 6.

FIG. 8 is a view of the FIG. 6 fragment shown at a processing stagesubsequent to that of FIG. 7.

FIG. 9 is a view of the FIG. 6 fragment shown at a processing stagesubsequent to that of FIG. 8.

FIG. 10 is a view of the FIG. 6 fragment shown at a processing stagesubsequent to that of FIG. 9.

FIG. 11 is a view of the FIG. 6 fragment shown at a processing stagesubsequent to that of FIG. 10.

FIG. 12 is a view of the FIG. 6 fragment shown at a processing stagesubsequent to that of FIG. 11.

FIG. 13 is a view of the FIG. 6 fragment shown at a processing stagesubsequent to that of FIG. 12.

FIG. 14 is a view of the FIG. 6 fragment shown at a processing stagesubsequent to that of FIG. 7 in accordance with a second aspect of thepresent invention.

FIG. 15 is a view of the FIG. 14 fragment subsequent to that of FIG. 14.

FIG. 16 is a view of the FIG. 14 fragment shown at a processing stagesubsequent to that of FIG. 15.

FIG. 17 is a diagrammatic, cross-sectional view of an exemplarydeposition apparatus which can be utilized in various aspects of thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This disclosure of the invention is submitted in furtherance of theconstitutional purposes of the U.S. Patent Laws “to promote the progressof science and useful arts” (Article 1, Section 8).

In particular aspects, the invention encompasses methods for formingsolder within openings extending through semiconductor components. Lowtemperature deposition is utilized to form a film within an opening. Thefilm can comprise a metal nitride, such as, for example, titaniumnitride. A surface of the film is plated with a solder-wetting material(such as, for example, nickel). The plating can comprise activation ofthe surface, (such as, for example, by dipping the film in a solutioncomprising hafnium and/or palladium), followed by electroless plating ofthe activated surface with the solder-wetting material. Alternatively,the plating can comprise utilization of activationless plating chemistryto form a plating on the surface. The activationless plating chemistrycan utilize reduced stabilizer content and can utilize the TiN of thefilm to carry an electrical potential for the plating chemical reaction.As another example, a low temperature TiN film can be used as a lowtemperature base or adhesion layer for another low temperature chemicalvapor deposited layer (such as, for example, tungsten). Thesolder-wetting material can then be plated onto the low temperaturechemical vapor deposited layer.

After formation of the solder-wetting material over the film, solder canbe drawn into the opening along the solder-wetting material to fill theopening.

The low-temperature deposition of the film is preferably conducted at atemperature of less than or equal to about 200° C. so that a temperatureof the semiconductor component does not exceed 200° C. during thedeposition. Suitable deposition technologies can comprise atomic layerdeposition (ALD) and/or chemical vapor deposition (CVD). To assist thereader in understanding the invention, ALD technology and CVD technologywill be initially described in some detail. Referring first to ALDtechnology, such typically involves formation of successive atomiclayers on a substrate. Such layers may comprise, for example, anepitaxial, polycrystalline, and/or amorphous material. ALD may also bereferred to as atomic layer epitaxy, atomic layer processing, etc.

Described in summary, ALD includes exposing an initial component to afirst chemical species to accomplish chemisorption of the species ontothe component. Theoretically, the chemisorption forms a monolayer thatis uniformly one atom or molecule thick on the entire exposed initialcomponent. In other words, a saturated monolayer. Practically, asfurther described below, chemisorption might not occur on all portionsof the component. Nevertheless, such an imperfect monolayer is still amonolayer in the context of this document. In many applications, merelya substantially saturated monolayer may be suitable. A substantiallysaturated monolayer is one that will still yield a deposited layerexhibiting the quality and/or properties desired for such layer.

The first species is purged from over the component and a secondchemical species is provided to chemisorb onto the first monolayer ofthe first species. The second species is then purged and the steps arerepeated with exposure of the second species monolayer to the firstspecies. In some cases, the two monolayers may be of the same species.Also, a third species or more may be successively chemisorbed and purgedjust as described for the first and second species. It is noted that oneor more of the first, second and third species can be mixed with inertgas to speed up pressure saturation within a reaction chamber.

Purging may involve a variety of techniques including, but not limitedto, contacting the component and/or monolayer with a carrier gas and/orlowering pressure to below the deposition pressure to reduce theconcentration of a species contacting the component and/or chemisorbedspecies. Examples of carrier gases include N₂, Ar, He, Ne, Kr, Xe, etc.Purging may instead include contacting the component and/or monolayerwith any substance that allows chemisorption byproducts to desorb andreduces the concentration of a species preparatory to introducinganother species. A suitable amount of purging can be determinedexperimentally as known to those skilled in the art. Purging time may besuccessively reduced to a purge time that yields an increase in filmgrowth rate. The increase in film growth rate might be an indication ofa change to a non-ALD process regime and may be used to establish apurge time limit.

ALD is often described as a self-limiting process, in that a finitenumber of sites exist on a component to which the first species may formchemical bonds. The second species might only bond to the first speciesand thus may also be self-limiting. Once all of the finite number ofsites on a component are bonded with a first species, the first specieswill often not bond to other of the first species already bonded withthe component. However, process conditions can be varied in ALD topromote such bonding and render ALD not self-limiting. Accordingly, ALDmay also encompass a species forming other than one monolayer at a timeby stacking of a species, forming a layer more than one atom or moleculethick. The various aspects of the present invention described herein areapplicable to any circumstance where ALD may be desired. It is furthernoted that local chemical reactions can occur during ALD (for instance,an incoming reactant molecule can displace a molecule from an existingsurface rather than forming a monolayer over the surface). To the extentthat such chemical reactions occur, they are generally confined withinthe uppermost monolayer of a surface.

Traditional ALD can occur within frequently-used ranges of temperatureand pressure and according to established purging criteria to achievethe desired formation of an overall ALD layer one monolayer at a time.Even so, ALD conditions can vary greatly depending on the particularprecursors, layer composition, deposition equipment, and other factorsaccording to criteria known by those skilled in the art. Maintaining thetraditional conditions of temperature, pressure, and purging minimizesunwanted reactions that may impact monolayer formation and quality ofthe resulting overall ALD layer. Accordingly, operating outside thetraditional temperature and pressure ranges may risk formation ofdefective monolayers.

The general technology of chemical vapor deposition (CVD) includes avariety of more specific processes, including, but not limited to,plasma-enhanced CVD and others. CVD is commonly used to formnon-selectively a complete, deposited material on a component. Onecharacteristic of CVD is the simultaneous presence of multiple speciesin the deposition chamber that react to form the deposited material.Such condition is contrasted with the purging criteria for traditionalALD wherein a component is contacted with a single deposition speciesthat chemisorbs to a component or previously deposited species. An ALDprocess regime may provide a simultaneously contacted plurality ofspecies of a type or under conditions such that ALD chemisorption,rather than CVD reaction occurs. Instead of reacting together, thespecies may chemisorb to a component or previously deposited species,providing a surface onto which subsequent species may next chemisorb toform a complete layer of desired material.

Under most CVD conditions, deposition occurs largely independent of thecomposition or surface properties of an underlying component. Bycontrast, chemisorption rate in ALD might be influenced by thecomposition, crystalline structure, and other properties of a componentor chemisorbed species. Other process conditions, for example, pressureand temperature, may also influence chemisorption rate. Accordingly,observation indicates that chemisorption might not occur appreciably onportions of a component though it occurs at a suitable rate on otherportions of the same component. Such a condition may introduceintolerable defects into a deposited material.

An exemplary method of the present invention is described with referenceto FIGS. 6-13. Referring initially to FIG. 6, such shows a fragment of aconstruction 200 at a preliminary processing stage. Construction 200comprises several of the structures described previously with referenceto FIGS. 1-5, and such structures are labeled identically inconstruction 200 as they were labeled in FIGS. 1-5. Accordingly,construction 200 is shown to comprise a semiconductor component 110having a front side 111 and a back side 113, and further is shown tocomprise a passivation layer 112 extending around component 110.Construction 200 further comprises a conductive metal trace 100analogous to the trace described previously, and comprises a thickpassivation layer 114 beneath trace 100. The thick passivation layer canbe, for example, a polyimide-containing layer.

Construction 200 differs from the construction 10 of FIGS. 1-5 in thatconstruction 200 comprises a pair of insulative-material layers 202 and204 over conductive-material layer 100. Insulative material layers 202and 204 can be referred to as a first and second insulative-materiallayer, respectively. Insulative-material layer 202 can comprise, forexample, polyimide, and insulative-material layer 204 can comprise, forexample, silicon dioxide formed by low-temperature deposition.Insulative-material layer 202 is patterned to have a gap 206 extendingtherethrough, which is ultimately to be a location for an outer leadbond.

Construction 200 can be considered a semiconductor component, and suchcomponent comprises a front-side surface 208 outwardly of the front sideof semiconductor die 110, and a back-side surface 210 outwardly of theback side 113 of die 110.

An opening 212 extends entirely through semiconductor component 200, andspecifically extends from front-side surface 208 to back-side surface210. Opening 212 comprises a depth 214 between the front-side surface208 and the back-side surface 210, and comprises a width 216 orthogonalto the depth 214. Opening 212 can have any suitable shape when viewedfrom above, including, for example, a substantially circular shape. Ifopening 212 is substantially circular when viewed from above, then width216 will correspond to a diameter of the circle. Regardless of the shapeof opening 212, the opening will have a maximum cross-sectional width.In particular aspects, such maximum cross-sectional width will be lessthan about 100 microns, and in further aspects such maximumcross-sectional width will be less than about 35 microns.

Opening 212 has sidewall peripheries 218 which comprise a surface ofpassivation material 112 and a surface of insulative material 204. Inparticular aspects, materials 204 and 112 can comprise the samecomposition as one another, and specifically can comprise, consistessentially of, or consist of silicon dioxide. Accordingly, sidewalls218 can comprise, consist essentially of, or consist of silicon dioxidealong the entirety of the sidewalls.

As discussed previously, structure 110 can comprise a semiconductor die,and in particular aspects will comprise a monocrystalline semiconductormaterial, such as, for example, a monocrystalline silicon wafer.Accordingly, opening 212 can be considered to extend through amonocrystalline silicon wafer in some aspects of the invention.

It is noted that an interface between materials 204 and 112 should beshown in the opening 212 of FIG. 6 as such interface would be visiblebehind the plane of the opening. However, such interface is not shownwithin the opening in order to simplify the drawings. Generally,interfaces occurring behind the illustrated planes of thecross-sectional views of this disclosure will not be shown, except ininstances in which it is believed that the showing of such interfaceswill enhance clarity in the drawings and/or description.

Structures 114, 100, 202 and 204 can be considered to be proximate thefront side 111 of structure 110. Specifically, the structures 114, 100,202 and 204 are closer to the front side 111 than to the back side 113.

The processing described previously with reference to FIGS. 4 and 5showed a hole 130 punched through conductive material 100, andaccordingly the hole 130 comprised a periphery containing the conductivematerial 100. A difference between the FIG. 6 structure 200 and thestructure described with reference to FIGS. 4 and 5 is that hole 212does not comprise a periphery extending entirely to conductive material100. Construction 200 can be formed by initially formingconductive-material layer 100 to be patterned such that the material 100comprises a gap extending therethrough where hole 212 is ultimately tobe formed. The gap can then be filled with the electrically-insulativematerial 204, and the opening 212 can be punched throughelectrically-insulative material 204.

Although construction 200 is shown with opening 212 not contactingconductive material 100, it is to be understood that the processing ofFIGS. 4 and 5 could be utilized instead of the shown processing.Accordingly the opening could be formed through a conductive pad ofmaterial as shown in FIGS. 4 and 5, and could have a peripherycomprising the conductive material of the pad.

Referring next to FIG. 7, a layer (which can also be referred to hereinas a film) 220 is deposited within opening 212 along sidewalls 218, andalso along back-side surface 210 of component 200. Layer 220 cancomprise an electrically-conductive material, and in particular aspectswill comprise, consist essentially of, or consist of metal nitride. Forinstance, layer 220 can comprise, consist essentially of, or consist ofone or more of titanium nitride, tungsten nitride, tantalum nitride andhafnium nitride. Layer 220 can be referred to as a first material inparticular aspects of the invention to distinguish layer 220 fromsubsequent materials formed within opening 212.

Although layer 220 is described as being formed over back-side surface210, it is to be understood that layer 220 can be alternativelyconsidered to define a new back-side surface so that the back-sidesurface 210 becomes associated with layer 220 rather than with material112. However, as will become apparent from the discussion that follows,the portion of layer 220 associated with the back side of construction200 is ultimately removed, so it is simpler for the discussion herein ifthe back-side surface is considered to remain associated with material112 even after formation of layer 220.

Layer 220 can be formed by, for example, ALD and/or CVD, and ispreferably formed at a temperature of less than or equal to about 200°C. The utilization of temperatures at or below 200° C. can avoidproblems discussed above in the “Background” section of this disclosure,and specifically can avoid heating circuitry associated with die 110(not shown) to temperatures which can adversely impact the circuitry.

FIG. 17 shows an exemplary deposition apparatus 1000 that can beutilized for forming layer 220. Apparatus 1000 comprises a reactionchamber 1002. An inlet 1004 extends into the reaction chamber, and avalve 1006 is provided across inlet 1004 for controlling flow ofmaterials through the inlet. An outlet 1008 also extends into thereaction chamber, and a valve 1010 is provided to control flow ofmaterials through the outlet.

A substrate holder 1012 is provided within the reaction chamber, andsuch is shown holding an exemplary substrate 1014. Substrate 1014 cancorrespond to, for example, the semiconductor component 200 of FIGS. 6and 7.

In operation, materials are flowed into chamber 1002 through inlet 1004,and expelled from chamber 1002 through outlet 1008. The materials flowedinto the chamber are represented by arrow 1016, and the materialsexpelled from the chamber represented by arrow 1018. The materialsflowed into chamber 1002 can be suitable reactants (i.e., one or moreprecursors), carrier gases, purge gases, etc.

If apparatus 1000 is utilized for an ALD-type process, two precursorscan be introduced into the chamber at different and substantiallynon-overlapping time intervals relative to one another. Specifically, afirst precursor can be introduced into the chamber to form a firstsubstantially-saturated monolayer over an exposed surface of substrate1014, and subsequently the first precursor can be expelled from thereaction chamber. A second precursor can then be introduced into thereaction chamber to react with the monolayer formed from the firstprecursor to form a desired material from the monolayer. The utilizationof the first and second precursors can be considered one cycle of theprocess, and multiple cycles can be utilized to form a desired materialto a desired thickness. The first and second precursors are described asbeing within the chamber at “non-overlapping time intervals” relative toone another in that each of the precursors is substantially entirelyflushed from within the reaction chamber prior to introduction of theother. The term “substantially” non-overlapping time interval isutilized to indicate that there may be some residual precursor withinthe chamber when a subsequent precursor is introduced into the chamber,but such residual precursor concentration will be very low, andtypically low enough so that there is no detectable interaction of theprecursors with one another except at the surface of substrate 1014.

In an exemplary aspect of the invention, layer 220 comprises metalnitride. In such aspect, a first precursor can comprise the metal of themetal nitride and a second precursor can comprise the nitrogen of themetal nitride. The layer 220 can be formed utilizing at least one cyclein which the first and second precursors are in the reaction chamber atdifferent and substantially non-overlapping time intervals relative toone another. Typically, each cycle will comprise introduction of thefirst precursor, followed by a purge, and then followed by introductionof the second precursor. If the metal nitride is titanium nitride,exemplary precursors containing the metal of the titanium nitride areTiCl₄ and tetrakis-dimethyl-amido-titanium (TDMAT), and an exemplaryprecursor containing the nitrogen of the metal nitride is ammonia (NH₃).

A titanium nitride layer 220 can be formed at a temperature of fromabout 68° C. to about 400° C. if formed from titanium tetrachloride andammonia, but preferably will be formed at a temperature of less thanabout 200° C.

In applications in which layer 220 is titanium nitride, the firstprecursor comprises TDMAT and the second precursor comprises ammonia,the formation of layer 220 can be accomplished utilizing multiple cyclesat a temperature of from about 100° C. to about 180° C., typically fromabout 130° C. to about 170° C., with an exemplary temperature being 155°C.; a pressure from about 200 milliTorr to about 2 Torr, with anexemplary pressure being about 800 milliTorr; a cold wall reactionchamber; a pulse of the TDMAT into the chamber for a time of about 1second; a purge for a time of about 10 seconds; and a second pulse ofthe ammonia into the reaction chamber for at time of about 4 seconds.The pulse of the ammonia can be followed by a purge for about 10seconds, to complete an individual cycle. The purge can be accomplishedutilizing vacuum and/or a suitable purge gas. The purge gas cancomprise, for example, argon, and is preferably a gas which is inertrelative to reaction with the precursors and any exposed materials onthe substrate.

The temperatures described above for formation of a metal nitride layerare exemplary temperatures. It can be preferred, however, thattemperatures utilized for formation of the layer 220 be at or belowabout 200° C., and more preferred that the temperatures be at or belowabout 160° C.

Layer 220 can be formed to any desired thickness through multiple cyclesof an ALD-type process. A typical thickness of layer 220 will be atleast about 100 Å, with exemplary thicknesses being from about 100 Å toabout 3000 Å. If the TDMAT/NH₃ processing is utilized, each of theabove-described cycles will typically form a layer less than or equal toabout 10 Å thick (with typical layers being about 9 Å thick), andaccordingly it can be desired to repeat the cycles at least about 10times to form layer 220 to a desired thickness.

The methods described above for the TDMAT/NH₃ processing and theTiCl₄/NH₃ processing are ALD-like, in that the methods utilize twoprecursors which are provided in a reaction chamber at substantiallynon-overlapping times relative to one another. It is to be understood,however, that the processing utilized to form layer 220 can be anysuitable processing, including CVD-type processes.

It is noted that a TiN film formed from TDMAT will frequently oxidizeupon exposure to air unless treated with a post-deposition anneal ofabout 400° C. As will become apparent below, the metal nitride film 220of the present invention is utilized as a substrate for a platingprocedure. In such applications, the conductive properties of the filmare not generally of concern, and accordingly, the film can oxidize tosome extent. Thus, the post-deposition anneal typically utilized withTDMAT formation of TiN can be omitted, and the film 220 can be formedwith a process which remains at or below 200° C. (typically at or below160° C., and frequently at or below 155° C.) for the entirety of theprocess.

Referring to FIG. 8, layer 220 is shown removed from over back-sidesurface 210 of component 200. Such removal can be accomplished utilizingany suitable etch, and/or utilizing planarization methods (such as, forexample, chemical-mechanical polishing).

FIG. 8 also shows a layer 222 formed over an exposed surface of layer220. Layer 222 represents activation of layer 220. The activation oflayer 220 is accomplished by exposing layer 220 to one or both ofhafnium and palladium. An exemplary method of activating a surface oflayer 220 is to expose the layer to a solution comprising about 0.15grams per liter of palladium chloride, and about 4 milliliters per literhydrofluoric acid, with the remainder being deionized water. Theexposure can be accomplished with a dip into the solution for a time offrom about 30 seconds to about 60 seconds, with about 30 secondstypically being adequate at room temperature. The activation can form aseparate layer 222 as shown, or can instead alter a surface compositionof layer 220. Regardless, the activation prepares layer 220 forsubsequent electroless deposition over the layer. In particular aspects,the activation forms the shown separate layer 222 comprising, consistingessentially of, or consisting of one or both of hafnium and palladium.Layer 222 can have a thickness of from about 1 micron to about 7microns, with an exemplary suitable thickness being about 5 microns.

The activation of the surface of layer 220 can be performed before orafter removal of layer 220 from over back-side surface 210. If layer 220comprises hafnium or palladium, the activation of the layer can beomitted.

Referring next to FIG. 9, a layer 224 is electroless plated ontoactivation layer 222. The material of layer 224 can be referred to as asecond material to distinguish the material from the first material oflayer 220. Layer 224 preferably comprises a solder-wettable material,and is formed within opening 212 to effectively line sidewalls of theopening with the solder-wettable material.

Layer 224 can comprise, consist essentially of, or consist of, forexample, nickel. In such aspects, layer 224 can be formed by dippingconstruction 200 into a nickel hypophosphate solution utilizing anoperating temperature of from about 59° C. to about 64° C., and adeposition time of from about 5 minutes to about 10 minutes. The nickelhypophosphate solution can be a solution manufactured by ShipleyCorporation for utilization with p-dimethylaminobenzaldeyhyde (DMAB)applications. The nickel hypophosphate solution will typically have a pHof from about 5 to 7, with a preferred pH being about 7. Theelectroless-plated layer 224 can have a thickness of from about 1 micronto about 7 microns, with about 5 microns being a preferred thickness. Ifthe thickness gets too low, a solder material formed over the nickellayer (the solder material is described below) can consume theelectroless-plated layer before the opening 212 is completely filledwith solder, so that the electroless-plated material does not accomplishthe desired task of providing adequate wetting for solder utilized tofill opening 212.

As discussed previously, activation and subsequent electroless platingis but one of many methods that can be utilized for plating asolder-wetting material over a metal nitride. Other methods include, forexample, activationless plating onto the metal nitride, and formation ofa low temperature chemical vapor deposited layer onto the metal nitridefollowed by plating onto the low temperature chemical vapor depositedlayer. If such other methods are utilized, the activation layer 222 canbe omitted, or can be substituted by a low temperature chemical vapordeposited layer. Alternatively, the activation layer can be formed overa low temperature chemical vapor deposited layer which in turn is formedover the metal nitride.

Although layer 224 is shown formed after removal of layer 220 from overback-side surface 210, it is to be understood that the inventionencompasses other aspects in which electroless-plated material 224 isprovided prior to removal of layer 220 from over the back-side surface,and in which both the electroless-plated material and material 220 areremoved from over the back-side surface.

Referring to FIG. 10, insulative-material layer 204 (FIG. 9) is removedto leave an opening 232 in the polyimide-containing layer 202 where anouter lead bond is to be formed. Also, an upper region of opening 212 isextended to form a region 230 of the opening that extends entirelyacross the gap within conductive-material layer 100. Accordingly, theextended region 230 of opening 212 has a periphery comprising an exposedsurface of conductive material 100. In particular aspects of theinvention, the opening 212 can be considered a first opening which doesnot extend to the conductive material 100, and the extended region 230can be considered a portion of the first opening which is extended toreach the conductive material 100. The formation of extended region 230can be accomplished utilizing any suitable etch. Although an entirety ofinsulative material 204 is shown removed during formation of extendedregion 230, it is to be understood that the invention encompasses otheraspects in which only a portion of material 204 is removed to form theextended region 230. Regardless, at least some of the material 204 isremoved.

In the shown aspect of the invention, the formation of extended region230 occurs after activation of first material 220, and also afterformation of electroless-plated material 224. It is to be understood,however, that the invention encompasses other aspects in which theextended region 230 is formed before one or both of the activation ofmaterial 220 and formation of plated material 224.

The removal of layer 204 (FIG. 9) changes the location of front-sidesurface 208 so that the surface is now associated with a surface oflayer 202 rather than with a surface of layer 204.

Referring to FIG. 11, a solder 240 is provided within opening 212 andwithin extended region 230. Solder 240 can be provided by, for example,utilizing wave-solder methodologies which apply the solder from a backside of the component 200. Accordingly, the solder fills opening 212,but does not extend into other typographical features associated withthe front side of component 200, including, for example, the opening232.

Solder 240 can comprise any suitable solder composition, including, forexample, compositions containing 63% tin and 37% lead (by weight), 96.5%tin and 3.4% silver (by weight), or 96.5% tin, 3% silver and 0.5% copper(by weight).

The solder-wetting material 224 advantageously assists in allowing thesolder to flow into narrow opening 212 at relatively low temperatures,while providing a uniform, quality fill within the opening. Exemplarytemperatures for provision of the solder within the opening are at orbelow about 200° C.

Referring to FIG. 12, a conductive-material layer 250 is formed overexposed conductive materials 100 and 240 on front surface 208. Theconductive material 250 can comprise, consist essentially of, or consistof, for example, nickel, and can be formed utilizing electroless-platingtechnology. The conductive material 250 within gap 232 forms a portionof an outer lead 252. The conductive material 250, together with solder240, forms an inner lead 254 which extends within opening 212.

Referring to FIG. 13, polyamide-containing material 202 (FIG. 12) isremoved, and a solder ball 260 is formed over the conductive material250 of outer lead 252. The removal of material 202 shifts the front-sidesurface 208 of component 200 to outer surfaces of trace 100, material114, and exposed materials 250 and 260. Although the solder ball 260 isshown selectively formed over material 250 of outer lead 252, and notover material 250 of inner lead 254, it is to be understood that asolder ball could also be formed over the inner lead.

The processing of FIGS. 6-13 illustrates one exemplary aspect of theinvention. Another exemplary aspect is described with reference to FIGS.14-16. In referring to FIGS. 14-16, identical numbering will be used aswas utilized above in describing FIGS. 6-13, where appropriate.

FIG. 14 illustrates a construction 300 at a processing step subsequentto that of FIG. 7. Expanded region 230 has been formed after formationof conductive material 220, and prior to removal of conductive material220 from back-side surface 210 of the component.

FIG. 15 shows activation layer 222 and electroless-plated layer 224formed along material 220. FIG. 15 also shows material 220 removed fromover back-side surface 210. Such removal can occur before or afterformation of one or both of activating layer 222 and electroless-platedlayer 224. Additionally, FIG. 15 shows removal of insulative material204 (FIG. 14) from over polyamide-containing material 202, which leavesa gap 232 exposed to a location where an outer lead is to be formed. Theremoval of material 204 preferably occurs after formation of activatinglayer 222 and electroless-plated layer 224, in order to avoid formationof an electroless-plated material on the conductive material 100 withinopening 232. However, the invention encompasses other aspects (notshown) wherein it is desired to form an electroless-plated materialwithin opening 232 simultaneously to forming the electroless-platingmaterial 224, and such aspects it can be desired to expose theconductive material 100 within opening 232 to the conditions utilizedfor forming layers 222 and 224.

Referring to FIG. 16, solder 240 is provided within opening 212 andextended region 230, conductive-material caps 250 are provided withinregions 230 and 232 (the region 232 is labeled in FIG. 15), and a solderball 260 is provided over the conductive material 250 in opening 232.The construction of FIG. 16 is comparable to the construction of FIG.13, but differs in that polyamide-containing material 202 has been leftover the construction of FIG. 16 during formation of solder ball 260, inaccordance with an alternative aspect of the invention relative to thatof FIG. 13.

The low-temperature processing of the present invention can providenumerous advantages. For instance, the process can be utilized inso-called “back-end” processes where heating above the low temperaturesutilized in the invention can be detrimental or is simply not possible.Additionally, methodology of the invention can be utilized withmetallization of plastics and other materials that may be sensitive totemperature.

In compliance with the statute, the invention has been described inlanguage more or less specific as to structural and methodical features.It is to be understood, however, that the invention is not limited tothe specific features shown and described, since the means hereindisclosed comprise preferred forms of putting the invention into effect.The invention is, therefore, claimed in any of its forms ormodifications within the proper scope of the appended claimsappropriately interpreted in accordance with the doctrine ofequivalents.

1-42. (canceled)
 43. A method of fabricating an interconnect for asemiconductor component, comprising: providing a semiconductorcomponent, the component comprising a monocrystalline semiconductormaterial having a pair of opposing sides, the component comprising afront side outwardly of one of the opposing sides of the monocrystallinesemiconductor material and a back side outwardly of the other of theopposing sides of the monocrystalline semiconductor material, thecomponent further comprising a conductive-material layer proximate thefront side; forming an opening which extends from the front side to theback side and thus extends entirely through the semiconductor component,the opening having sidewalls and extending through theconductive-material layer; depositing a first material along thesidewalls of the opening to narrow the opening, the depositing utilizingone or more cycles of a process which forms less than or equal to about10 Å of the first material per cycle and which exposes the component toa temperature of less than or equal to about 200° C.; forming asolder-wetting material within the opening and along the first material;and forming solder along the solder-wetting material to fill the openingwith solder; the solder within the opening electrically connecting withthe conductive-material layer.
 44. The method of claim 43 wherein thefirst material is a metal nitride and wherein the process is conductedin a reaction chamber utilizing: a first precursor containing the metalof the metal nitride; a second precursor containing the nitrogen of themetal nitride; and provision of the first and second precursors in thereaction chamber at different and substantially non-overlapping timeintervals relative to one another.
 45. The method of claim 44 whereinthe metal nitride is titanium nitride, tungsten nitride, tantalumnitride or hafnium nitride.
 46. The method of claim 44 wherein the metalnitride is titanium nitride.
 47. The method of claim 46 wherein thefirst precursor is TiCl₄ and the second precursor is NH₃.
 48. The methodof claim 46 wherein the first precursor is TDMAT and the secondprecursor is NH₃.
 49. The method of claim 48 wherein the processutilizes, in the following sequential order, a first pulse of the TDMATinto the reaction chamber, a substantial purge of the TDMAT from thereaction chamber, and a second pulse of the NH₃ into the reactionchamber.
 50. The method of claim 43 wherein the semiconductor componentcomprises a first insulative-material layer over the conductive-materiallayer and a second insulative-material layer over the firstinsulative-material layer, and wherein the second insulative-materiallayer has a surface corresponding to the front side of the semiconductorcomponent.
 51. The method of claim 50 wherein the firstinsulative-material layer comprises polyimide and the secondinsulative-material layer comprises silicon dioxide.
 52. The method ofclaim 43 wherein a gap extends through the conductive-material layer,and wherein the forming the opening comprises: forming a first openingwithin the gap, the first opening not extending to theconductive-material layer; and extending a portion of the first openingto the conductive-material layer.
 53. The method of claim 52 wherein theextending occurs prior to the forming of the solder-wetting material.54. The method of claim 52 wherein the forming of the solder-wettingmaterial comprises electroless plating of the solder-wetting material.55. The method of claim 54 wherein the first material comprises a metalnitride, and further comprising activating the metal nitride with one orboth of Hf and Pd prior to the electroless plating.
 56. The method ofclaim 55 wherein the activating occurs prior to the extending.
 57. Themethod of claim 55 wherein the activating occurs after the extending.58. The method of claim 54 wherein the extending occurs after theelectroless plating.
 59. The method of claim 52 further comprisingforming an electrically-insulative material over the conductive materialand within the gap in the layer of conductive material, wherein thefirst opening extends through the electrically-insulative material, andwherein the extending comprises removing at least a portion of theelectrically-insulative material.
 60. The method of claim 59 wherein theelectrically-insulative material comprises a silicon dioxide-containinglayer.
 61. The method of claim 60 further comprising forming apolymide-containing layer over the layer of conductive material, andwherein the silicon dioxide-containing layer is over thepolymide-containing layer.
 62. The method of claim 43 wherein the firstmaterial comprises a metal nitride.
 63. The method of claim 43 whereinthe first material consists essentially of a metal nitride.
 64. Themethod of claim 43 wherein the first material consists of a metalnitride.
 65. The method of claim 43 wherein the first material comprisesone or more of titanium nitride, tungsten nitride, tantalum nitride andhafnium nitride.
 66. The method of claim 43 wherein the first materialconsists essentially of one or more of titanium nitride, tungstennitride, tantalum nitride and hafnium nitride.
 67. The method of claim43 wherein the first material consists of one or more of titaniumnitride, tungsten nitride, tantalum nitride and hafnium nitride.
 68. Themethod of claim 43 wherein the forming of the solder-wetting materialcomprises electroless plating of the solder-wetting material.
 69. Themethod of claim 68 wherein the first material comprises a metal nitride,and further comprising activating the metal nitride with one or both ofHf and Pd prior to the electroless plating.
 70. The method of claim 43wherein the depositing forms the first material along the back side ofthe semiconductor wafer, and further comprising removing the firstmaterial from over the back side of the semiconductor wafer.
 71. Themethod of claim 70 wherein the forming of the solder-wetting materialcomprises electroless plating of the solder-wetting material, andwherein the removing occurs prior to the electroless plating.
 72. Themethod of claim 71 wherein the first material comprises a metal nitride,and further comprising activating the metal nitride with one or both ofHf and Pd prior to the electroless plating.
 73. The method of claim 72wherein the activating occurs prior to the removing.
 74. The method ofclaim 72 wherein the activating occurs after the removing.
 75. Themethod of claim 70 wherein the forming of the solder-wetting materialcomprises electroless plating of the solder-wetting material, andwherein the removing occurs after the electroless plating.